It'd be like somebody sticking an extra hard drive or NIC in the computer you built at home and you not noticing it.
No, it'd be like you buying a NIC and installing it without realizing there was a backdoor in its firmware. Not everything in a satellite is a one-off custom piece, a lot of it is COTS and integrated by the builders.
There's a very strong bias here on HN that everything is software. But Satellite assembly is very much a HW thing as well. Attributing whatever it is to a specific country lends itself to being hardware more than software, probably some parts that have very few or one supplier so the country of origin can be determined.
No, it'd be like you buying a NIC and installing it without realizing there was a backdoor in its firmware. Not everything in a satellite is a one-off custom piece, a lot of it is COTS and integrated by the builders.